1. Field of the Invention
The present invention relates to a technology for achieving power savings in a device for performing communication.
2. Description of the Related Art
In recent years, power savings in various devices have been in progress. As an example of technologies for such power savings, a technology comes into widespread use by which supply of electricity to a part of hardware of a device is temporarily limited.
Such technologies are used also in an image forming apparatus into which functions of copying, PC printing, faxing, scanning, box function, and so on are consolidated. Such an image forming apparatus is usually called an “MFP” or a “multifunction device”.
Limiting the supply of electricity, however, sometimes affects the operation. To cope with this, the following method has been proposed.
An MFP is provided with an automatic response unit, an analysis unit, a message generation unit, and a transmitting/receiving unit. The automatic response unit switches the mode from a power-saving mode to a normal mode based on a protocol requested by a PC. The analysis unit analyzes whether or not the PC is in a state of requesting the protocol for switching the mode from the power-saving mode to the normal mode without executing a job. The message generation unit generates, when the analysis unit detects the state, a message for changing the protocol the PC has. The transmitting/receiving unit transmits the generated message. Thereby, it is possible to reduce the possibility that the mode is switched from the power-saving mode to the normal mode for the case where a request not directly related to printing is received (Japanese Laid-open Patent Publication No. 2012-179788).
The following method has also been proposed. An image processor having a first power mode and a second power mode whose power consumption is smaller than that of the first power mode, includes: a first control part for controlling the entirety of the device; and a second control part to which power is supplied in the first power mode and the second power mode, and then, performs security communication with an external device. The first control part selects security-related information to be reported to the second control part among a plurality of pieces of security-related information stored in a storage part for storing the plurality of pieces of security-related information associated with the security communication when the first power mode is shifted to the second power mode (Japanese Laid-open Patent Publication No. 2012-227829).
Further, another technology has been proposed in which, in a power-saving mode, a sub CPU is used to respond to a part of received packets without the use of a main CPU.
According to the conventional technologies, it is necessary to arrange, at the design stage of a device, whether a main CPU performs processing for responding to received packets or whether a sub CPU performs the processing in place of the main CPU.
In recent years, a variety of protocols have been used in networks. In what way such protocols are used is varied and may be changed. There is a variety of network configurations, and the configurations may be changed. Accordingly, which of the main CPU and the sub CPU should respond to received packets may change while the device is used.